If you have specified high-performance windows, you may already know that low-conductivity gases such as argon, xenon, and krypton can significantly improve the energy performance of windows. These gases have lower gas-phase conductivity than air, so they retard heat flow through the window.

And while these gases are nontoxic, they are expensive and could lead to the depletion of other resources, according to Nadav Malin, president of BuildingGreen and Vision 2020 chairman. “Noble gases aren't exactly in short supply, but it's very expensive to isolate them,” he explains. “Right now, supplies are available as a by-product of isolating other gases, but those supplies may soon be outstripped.”

Malin says that while builders can continue to use gas-injected, high-performance windows for now, they should keep their eyes out for further developments in this rapidly changing industry. The next generation of energy-savings windows is likely just around the corner.